VISONIC MCT427 WIRELESS SMOKE & HEAT DETECTOR, UL Modern design suitable for residential and commercial applications Activates an alarm when the temperature reaches 60C (140F) and starts increasing rapidly Loud (85db) alarm sound at 3m (10ft) 5 or 8 years battery life (according to the battery type) and easy battery replacement Fully certified by the most strict and demanding international standards for safety products in Europe (EN 14604) and USA (UL 268)